JEITA CP-3451 - 70 - Stipulations on image height Image height information consists of the valid image height tag (PixelYDimension), SOF marker information, and JPEG compressed data. Of these three, the recording of a valid image height tag is mandatory. The image height is padded in the following case. The padding value is not specified. a)     When the image height is not an exact multiple of 16 and the JPEG block has unused capacity to be filled. Insertion of a restart marker does not require padding. The method of recording the various image height data with and without padding  is  given  in  Figure  31.  The  SOF  marker  always  has  the same  value as  the effective  image height tag.   Figure 31 Image Data Height Description Table 20 gives examples of information recorded in the direction of image height and padding data height, for each of cases A, B, and C of Figure 31. Table 20 Typical Height Direction Information and Padding Data (when Y:Cb:Cr = 4:2:2) Valid Image Height Valid Image Height Tag SOF Information Compressed Data Padding Height A 480 480 480 480 0   B 474 474 474 480 6 (< 1MCU) C 460 460 460 464 4 (< 1MCU) B.    Image size reproduction procedure in the Exif reader It is recommended that the Exif reader (and in particular, dedicated software) follow the procedure shown in Figure 32 for reproducing images. First it expands the image based on the SOF information. Next it trims the image on the right and lower edges in accord with information in the valid image width tag and height tag, and reproduces the valid  image  data.  If  the  SOF  information  and  the  valid  image  width  and  height  tag  information  are  the  same, trimming is unnecessary.   X=multiple of 16 ? PixelYDimension = Y SOF.Y = Y Padding in multiple of 64 ? JPEG Compression No Yes Y : Valid Image length SOF.Y : Vertical line value in SOF PixelYDimension   : PixelYDimension value A B,C